When is the fruit ready on a Japanese Plum Tree?

Yay! How lucky are you! Here are some sites to help you out.

https://homeguides.sfgate.com/season-japanese-plum-tree-fruit-it-61440.html

https://www.gardeningknowhow.com/edible/fruits/plum/satsuma-plum-care.htm

Cut one open and try it. If sour or bitter, not ready yet.

The Japanese plum tree is mostly ornamental. When you can split a plum and see full grown seeds inside, taste the plum. If you like it, the rest of the plums can be eaten.

Best wishes!

We had one. When they turn yellow & are slightly soft. Wash & eat.

All good answers, my plums are ready late June to mid July, store in small containers

keep in cool area, Tasty, if they come of easy with stem or w/out an semi firm, they are ready "Enjoy" Tr.